I am running Mint KDE 9 (Isadora) on a triple boot desktop with Windows XP and Mint KDE 8 (that I do not use anymore). I am connected to the internet through cable at my work. This week I haven't been able to get onto the the net on Monday, Wednesday and today (Friday) using Mint. The internet works fine on the Windows part as well as from a laptop (Mint KDE 12 - Lisa). I do get a dynamic ip address and and I am using the same dns servers on the desktop and the laptop, so I am really very confused and could do with some help.

I include some of the output that helpful people usually ask for when trying to help with network issues below. It may not be very useful; output from ifconfig and contents of /etc/resolv.config and /etc/network/interfaces look similar to the output on the laptop, nslookup and ping does not (if fails on the desktop, works on the laptop). Let me know if you need anything else.

feodor:~/>cat /etc/resolv.conf # Generated by NetworkManager nameserver 130.226.32.32nameserver 208.67.222.222nameserver 208.67.220.220# NOTE: the libc resolver may not support more than 3 nameservers.# The nameservers listed below may not be recognized.nameserver 130.226.32.39

Thank you for your answer. I have been online for the last two days without any problems. So my problem is gone for now but it has not been solved and that bugs me. It also means that there will be little use in trying the things you suggested at this point. I will keep them in mind if the problem reoccurs.

The first DNS server turns out to be my university's DNS server; it probably cannot be pinged from the outside. When I wrote, I was able to ping it from my laptop (wireless as well as cabled). I tried pinging a few ip-addresses but was not able to ping any of them from my desktop. The problem remained with OpenDNS as my first DNS server. So, I do not think the problem is a DNS problem.